When her sister Elena flees to Paris, Anna's mother, Marian, uses a bankruptcy summons to force her to take Elena's place as a bride at Merton Manor. There, Anna is wed to Leo, the reclusive master of the estate, who wears an iron mask and shuns the light. After the elderly butler Arthur gives her a brass key adorned with a beast's head and warns her to stay out of the west wing, Anna soon discovers that Leo's supposed disfigurement and fear of light conceal a darker truth: he has been poisoned by his own brother, Julian. While Leo lies gravely ill, Julian is seizing control of the family empire, aided by the legal adviser Vance, who is forging documents to remove Leo from power. Remaining steadfastly by Leo's side, Anna uses her compassion and loyalty to unravel the murder plot—and reclaim the manor for them both.
